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The Bug With Fast Growing Bifocal Eyes

To the non-scientist, the Sunburst Diving Beetle doesn't look any different than your average beetle. But put it under a microscope and examine the complexity of its eyes. You will see bifocal eyes-six sets of them.

Credit Elke Buschbeck / University of Cincinnati
Head of third instar larva

Dr. Elke Buschbeck, a University of Cincinnati professor of biological sciences and graduate student Shannon Werner discovered the Sunburst Diving Beetle has bifocals, the only insect with them so far. Their research, explaining the quick development of the eye structure, is published in this edition of the Journal of Comparative Physiology A.

According to Buschbeck, "It (bifocals) allows them to use 2 different photoreceptive tissues at the same time to look at the same thing in a distance or the same thing in close-by....we think it allows the beetle to see quite a lot at the same time"

This Discovery Magazine article explains how Buschbeck discovered the bug has bifocal eyes.

Other interesting findings about the bug's eye:

  • It has Multiple retinas
  • It can see polarized light
  • It is very good at seeing underwater
  • It is similar to human eyes

Buschbeck says in just 30 minutes to an hour the bug makes changes to its eyes as it goes through  three larval stages. She thinks it may have something to do with osmotic pressure. Osmotic pressure is defined as the force caused by a solution passing through a semi permeable surface by osmosis.
During this extremely rapid eye growth the Sunburst Diving Beetle temporarily goes blind. The lens is reformed quickly and vision is sharpened again. This takes about 8 hours. Buschbeck explains as soon as she can measure it, it has already grown. UC scientists feed and check on the bugs daily. Ones in the larva stage are kept in cups. Fully grown beetles go into the aquarium.

Buschbeck says the rapid eye expansion suggests a certain level of pre-determined eye growth, but specific adjustments also could be made at the level of the lens, which takes longer to reform. Changes are being made to the bifocal lenses as well.

“We think it allows the beetle to see quite a lot at the same time because it can see with those two different photo receptive structures at the same time, so that is really different from other insects or any other animal for that matter.”

Studying the structure of these eyes can help doctors learn more about human eyes. The study is also helping to improve cameras. Buschbeck’s research may also aid in developing a special type of camera.

“So those who are familiar with photography, it’s always hard to have things in focus, which is far away and which is close-up. So, using that insect’s principle to build a camera which can see distance and close-up at the same time will help.”

The National Science Foundation is funding Buschbeck’s research on the Sunburst Diving Beetle.

This story was originally published November 23, 2015.